Teensy Adapter for RetroShield

Name: Teensy Adapter for RetroShield
SKU: 18914
Price: 18.00 USD
Availability: InStock
Rating: 4.85 (5 reviews)

(5 Reviews)

Add super powers to your RetroShields

Designed by 8-Bit-Force in United States of America

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Add super powers to your RetroShields

2023-08-29: Holding off international shipments until I figure out the updated fees. Please stay tuned. Warning: This requires Teensy 3.5 or 3.6 boards which are out of production. What is it? This b…

What is it?

This board lets you connect your RetroShields to Teensy 3.5 and add super-powers to your 8bit microprocessor :)

Uses Teensy 3.5 (sold separately here)
much faster (120Mhz ARM vs 16Mhz ATMega)
more memory (256 KB vs 6K)
micro SDCard connector
Same simple development tools (use existing Arduino IDE programming environment with fast compilation)
8-bit Microprocessors run much faster (6502 and 6809 close to 1.0Mhz clock speeds).

This board also supports NGT30 Video/Keyboard Shield. I like NGT30 because it is possible to make your own stand-alone computer :)

What do you get?

Two options:

PCB w/ SMT parts soldered.
Kit: PCB + connectors

Why did you make it?

Teensy is faster and more capable platform than Arduino, however I had two issues w/ existing Teensy adapter boards:

First was voltage level mismatch. Teensy 3.5 is advertised as 5V-tolerant. What it really means is its inputs are 5V-tolerant. It still outputs 3.3V signals. For most 5V devices, 3.3V is high enough to register logic-high but some microprocessors wanted higher voltages. These did not work reliably or not work at all. Hence I needed true 3.3V <-> 5.0V level shifting.

Second, we read 16bits of address bus and read/write 8bits of data bus to/from the processors. Existing teensy adapters required reading several bit at different gpios and then several bit shift/or/and operations. This wasted precious teensy cycles. I reassigned the Teensy gpio's in groups of 8bit ports to the arduino mega header so reading databus and/or address buses take single cycle teensy instructions. This helps us run the microprocessor fast.

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Review Breakdown

Average Ratings

Product: (5.00)

Documentation: (4.60)

Shipping: (5.00)

Communication: (4.80)

Tim | May 11, 2021

Great fun and useful for reliving my Z80 days.

I've been a software engineer for over 30 years but stll hark back to my Z80 days in the early eighties. This works really well and doubles up as a Z80 chip checker for me. I would recommend this to anyone with a taste for retro-computing. I've ony used it with the Z80 RetroShield so far although I have the 6502, the 6803, 1802 and the 6809 boards also. Most of these are unfamiliar to me and I look forward to doing a bit of retro-exploration. Easy enough to use but not recommended for absolute beginners (need to be familiar with Arduino, handy with soldering and have some knowledge of 8-bit micros to get the best out of the kits.). Also handy as an interface board for the teensy as it gives you a bunch of 5V I/O pins which can be used for other purposes besides RetroSheild use.

Pierre | March 3, 2021

Full speed RetroShields

This board allows the old processors, 6809 for instance, to run a bit above 1MHz with a Teensy 3.6 where the Arduino Mega is ten times slower.

This speed allowed me to add many devices, emulated by the software, like a 7 segments display and a keyboard, and also an interface to the SD Card. They are seen as memory addresses by the RetroShield processor. The power of the Teensy 3.6 allows to stay above 1MHz most of the time.

I tried to adapt the software to the new Teensy 4.1, but its I/O registers are a bit different and force some modifications in the software. I must add that the software version for the Arduino Mega cannot run on the Teensy. You will have to take the right version, on https://gitlab.com/8bitforce/retroshield-teensy

The Teensy Adapter board is very easy to build. The PCB and components are of the best quality. All the documentation is perfect, and the schematics are not ugly at all, despite what the designer, Erturk Kocalar wrote :-)

I uploaded a small video on YouTube to demonstrate the Adapter and 6809 RetroShield : https://www.youtube.com/watch?v=1ehCcJTsoew

Jay | Aug. 7, 2020

Speed up your retro processor!

This was a great kit and easy to build. It took no time to get it up and running. My 6809 board runs so much faster with it. I also have the Z80 board that I will try soon.

John | June 15, 2020

Speed up my 6502 Retroshield x 4 times!

I love the Retroshield projects - they are a great way to tinker with 8-bit CPUs and systems. Previously, I was using the Arduino MEGA to host them, but I have now switched to this Teensy kit: I'd never used a Teensy and this was a good excuse to investigate it. Assembly was easy - just the connectors, switches and an LED. Once I programmed it and connected the shield, the CPU ran way faster - I'm estimating about 0.8Mhz which means it's very close to the original Apple 1 speed. Very happy with it!

Alessandro | May 14, 2020

Amazing

Erturk is passionate about his products and wants his Customers to succeed!
I was very excited to find out that 8-bit-Force had already designed what I needed for a 6809-based project.
The design is solid, and the application examples are extremely useful to get me up and running quickly.
In addition to the Retroshield for 6809, I also purchased the Retroshields for 6502 and for the Z80.